The present invention relates to a blood component deposition-preventing agent and a blood coagulation accelerator for use in the laboratory examination of a blood sample, particularly in hematology, serum biochemistry, and immunoserology, methods using them, and blood examination ware and matrixes.
With recent advances in testing techniques, the chemical, immunoserological and hematological examinations of blood have witnessed a remarkable mechanization so that it is by now certain that only if properly prepared samples were provided, such examinations could be carried through in short periods of time. For example, even in the outpatient setting, the doctor would be able to make a diagnosis based on blood examination data, thus contributing much to the diagnosis and therapy of diseases.
As to the pretreatment for hematological examinations using whole blood as a sample, mere admixing of the blood with an anticoagulant, which is not time-consuming, is sufficient so that the sample can be almost immediately set in an analyzer.
However, in biochemical or immunoserological examinations using the serum fraction of blood, it is necessary to coagulate the blood once and, then, separate the serum by centrifugation or the like and the procedure is rather time-consuming. Therefore, in order to reduce the time required for the whole examination procedure from the pretreatment of a sample to the output of test data, mere shortening of the analysis time by mechanization of the analytical procedure is insufficient and it is necessary to shorten the time required for separation of serum.
Meanwhile, glassware has heretofore been used as the blood examination vessel for accommodating the blood to be tested, allowing-it to coagulate therein, and separating the serum by centrifugation. However, glassware is vulnerable to mechanical impact and, when it is broken, the test sample that issues out or splashes may cause the examiner to be infected by pathogenic bacteria and, as an additional problem, the necessary blood sampling for reexamination adds to a burden on the patient. For these reasons, plastic vessels have come into popular use in recent years. However, such plastic ware has been found disadvantageous in that the formed elements of the blood (hereinafter referred to as blood components) such as platelets, various blood proteins, and especially the fibrins which are formed in the final stage of the blood coagulation process, are very liable to deposit on the inside wall of the plastic ware and thereby exert untoward effects on examination results. Moreover, as will be described in detail hereinafter, it is common practice to employ a mineral substance or an organic substance, such as ellagic acid, as a blood coagulation accelerator in blood examination ware but such blood coagulation accelerator tends to encourage deposition of said blood components on the vessel wall and the blood components once deposited will not easily be detached from the inside wall of the vessel under the routine conditions of centrifugation such as about 1000 to 1800 Gxc3x975 minutes. As a result, owing to the high shear force of centrifugation acting on the interface between the inside wall and the clot, the platelets and red blood cells are destroyed and their contents leak out to affect the examination results.
To overcome these disadvantages, Japanese Kokai Publication Sho-58-105063 and Japanese Kokai Publication Sho-58-105064 proposed a method which comprises disposing a blood coagulation accelerator and a nonionic surfactant concomitantly on the inside wall of the ware, for instance. However, with the resent rapid development of high sensitivity techniques in the field of immunoserological examination, analogues of nonionic surfactants are being used as sensitizers on more and more occasions. If the test serum is contaminated with a nonionic surfactant, oversensitizing reactions occur in immunoserologic parameters to present the problem of inaccuracy leading to false positive tests.
On the other hand, for efficient separation of plasma from the blood to be analyzed, there is a protocol involving addition of a blood anticoagulant such as an ethylenediaminetetraacetic acid salt or a citrate to the blood sample. In hematological examinations using an anticoagulant, too, the deposition of blood components, particularly platelets, on the plastic surface may be a cause of trouble, although the frequency of the trouble is not high. If platelets stick to the inside wall of blood test ware, the platelet count may show on abnormally low value or confound blood coagulation function values. Moreover, where an emergency chemical examination is required, it is common practice to use a heparin salt which is a kind of anticoagulant but if the deposition of platelets occurs in such cases, various enzymes of platelet orgin leak out into the plasma with time so that the related examination parameters tend to show abnormally high values. These events are less frequent as compared with the coagulation of blood and have so far attracted little attention but are now pointed out as serious problem as an omnibus, accurate and rapid blood examination is demanded.
The above problem of deposition of blood components has been pointed out with reference to plastic blood test ware but recently the adverse influences of the deposition and activation of platelets on examination results have been pointed out for blood examination glassware as well and improvements are being sought just as for plastic ware.
Since plastic ware for blood examination is intrinsically low in the potential to activate blood coagulation XII factor and XI factor, it takes by far a longer time for the blood to coagulate in plastic ware than in glassware and, therefore, plastic ware has so far been of low practical value.
Therefore, attempts have been made to shorten the blood coagulation time by coating the inside wall of blood test ware with a finely divided mineral substance such as glass, kaolin, bentonite, silica, cerite, or the like or a blood coagulation accelerator such as ellagic acid as taught in Japanese Kokai Publication Sho-58-195151 or accommodating in the ware a substantially blood-insoluble and chemically inert nonwoven cloth or plastic sheet matrix on which said finely divided particles have been immobilized as taught in Japanese Kokai Publication Sho-58-105064.
When a blood coagulation-accelerating substance is to be coated on the inside wall of a blood test ware or immobilized on a carrier, a suspension of finely divided particles of such substance either in pure water or in a mixture of alcohol and pure water is prepared and spray-coated on the inner surface of the ware or a carrier material is dipped in such a suspension, dried, cut to size, and accommodated within the blood test ware.
However, such a treating suspension is susceptible to the attack of microorganisms and unless it is properly handled, may cause contamination of a blood sample with microorganisms. Furthermore, when a water-soluble macromolecular compound such as polyvinylpyrrolidone or a modified cellulose is incorporated in said suspension as a binder for said coagulation accelerator powder or a viscosity adjusting agent for the suspension as is generally practiced, the water-soluble macromolecular compound serves as a good nutrient source for microorganisms so that the above-mentioned tendency of the treating suspension to be a microbial contamination risk factor is further encouraged.
As the proliferation of microorganisms progresses, condensation products will be accumulated in the treating suspension to cause troubles such as clogging of the spray nozzle, marked loss of coated surface evenness, and biases in the density of particles immobilized on the carrier in the dipping stage, all of which add up to measurement errors. The risk of microbial contamination is not confined to the current risk associated with degradation of the treating suspension but is a persistent drawback for the shelf-life of the ware unless the method for storage of the ware is wholesome.
Therefore, unless manufactured in a sterile environment, a blood test ware containing a blood coagulation accelerator may have to be sterilized with actinic radiation such as gamma-rays, electron beams, etc. or a chemically reactive gas such as ethylene oxide gas. In any of such procedures the radiation dose or the concentration of the reactive gas, heating temperature, exposure time and other sterilizing conditions must be adjusted according to the contamination status prior to sterilization and, thus, very delicate control is required.
Moreover, where the sterilizing load has been severely contaminated, rugged sterilizing conditions are required so that the load may sustain irreversible modification, deformation, and other damages. Moreover, in the storage after sterilization, the sterility once established will be jeopardized unless the ware is properly packaged.
One of the possible effective approaches to solving the above problems is to impart antimicrobial activity to the very coagulation accelerator. By such a technique, the above-mentioned microbial contamination would be inhibited and even if sterilization be needed, mild sterilizing conditions would be sufficient, with the result that the physical and chemical changes of the load due to sterilization could be prevented or suppressed. Furthermore, the packaging of the blood test ware could be simplified.
As regards antibacterial and antifungal agents which are generally used for prevention of microbial contamination, a large number of compounds inclusive of those for food use are already known and in use. However, the large majority of these antibacterial and antifungal agents are water-soluble and, therefore, if the blood is drawn into a blood test ware in which a blood anticoagulant supplemented with such an antimicrobial agent has been accommodated, the antimicrobial agent may dissolve out into the blood to confound various chemical tests. Moreover, when the antibacterial or antifungal agent is a water-soluble heavy metal salt, it modifies the enzymes associated with blood coagulation and the resulting deactivation of the enzymes prevent coagulation of the blood and make it difficult to achieve the objective such as separation of serum.
Where the specimen to be analyzed is plasma, it is a routine procedure to mix the blood with an anticoagulant and centrifuge the mixture to separate plasma from the solid fraction. Generally speaking, in order to avoid contamination of plasma with substances liberated from formed elements of the blood and other matter and the consequent interference with tests, the plasma obtained by centrifuging blood in the above manner is transferred to a different container and stored. Recently, however, for the purpose of protecting the examiner against infection via the patient""s blood, a procedure which does not require a transfer to another ware is demanded. Therefore, the use of a plasma separator comprising a thixotropic fluid as disclosed in Japanese Kokai Publication Hei-2-168159 or the use of a separator for provision of a partition between the plasma layer and the solid component layer as taught in Japanese Kokai Publication Hei-5-26873 has been recently employed.
However, the inside surface of the plastic ware is hydrophobic and the blood cells and proteins are adsorbed thereon as mentioned above. Particularly platelets are adsorbed with a high affinity and because LDH (lactic dehydrogenase), CPK (creatine kinase), K (potassium), etc. occur at higher levels in platelets than in plasma, these components are released from the platelets adsorbed on the plastic surface and it is inevitable that the values of these test parameters are considerably affected.
Therefore, even if the above-mentioned procedure of providing a partition between the plasma layer and the solid component layer is followed, the gradual release of enzymes and others from the blood cells adsorbed on the inside wall of the ware containing the plasma is unavoidable and interferes with tests. These adverse effects are particularly remarkable when the plasma is stored in the refrigerator for reexamination.
Having overcome the above disadvantages of the prior art, the present invention has for its primary object to provide a blood component deposition-preventing agent which is capable of inhibiting deposition of blood components effectively without causing the problem of false positive reactions in the immunoserological tests.
The second object of the present invention is to provide a blood coagulation accelerator comprising an antibacterial composition which has its own blood coagulation-accelerating activity and yet substantially does not interfere with blood coagulation activity or confound serum biochemical tests.
The third object of the present invention is to provide a plastic ware and a matrix for blood examination which do not influence test values owing to release of substances from blood cells even when used in tests on plasma.
The essential feature of the first aspect of the present invention is that a random copolymer comprising 10 to 90 mol % of a monomer component (a) the homopolymer of which is water-soluble and 90 to 10 mol % of a monomer component (b) the homopolymer of which is water-insoluble is used as a blood component deposition-preventing agent.
The essential feature of the second aspect of the present invention is that a blood coagulation accelerator is provided by supporting an antimicrobial metal on a carrier material and incorporating the resulting substantially blood-insoluble antimicrobial composition.
The essential feature of additional aspect of the present invention which is composed of first and second aspects resides in methods using said blood component deposition-preventing agent and said blood coagulation accelerator and in the blood test ware and matrix.
The first and second aspects of the present invention are now described in detail.
The blood component deposition-preventing agent according to the first aspect of the present invention comprises a random copolymer. The monomer component(a) as a constituent of said random copolymer is not limited in kind only if its homopolymer is water-soluble,thus including vinylpyrrolidone, vinyl alcohol, ethylene oxide, salts of acrylic acid, salts of styrenesulfonic acid, salts of vinyl phosphonic acid, allylamine salts, hydroxymethyl(meth)acrylate, glycosylethyl(meth)acrylate, saccharides such as glucose, amino acids such as glutamic acid, and so on. These monomers can be used singly or in combination.
The monomer component (b) as the other constituent of said random copolymer is not limited in kind, either, only if its homopolymer is water-insoluble, thus including ethylene, propylene, propylene oxide, vinyl acetate, vinyl chloride, alkyl(meth)acrylates, styrene, acrylonitrile, acrolein, and so on. These monomers can be used singly or in combination.
The random copolymer comprising said monomer component (a) and monomer component (b) can be provided by the known addition polymerization, polycondensation, or other technique.
However, from the standpoint of availability, it is advantageous to prepare the random copolymer using vinylpyrrolidone or vinyl alcohol as monomer component (a) and vinyl acetate as monomer component (b). As commercial products, Luviskol VA grade numbers VA73, VA64, VA55, VA37, and VA28 are available from BASF as typical vinylpyrrolidone-vinyl acetate random copolymers and Unitika Poval grade numbers E-180, UMR-10M, UMR-30L, and UMR-150L are available from Unitika Ltd. as typical vinyl alcohol-vinyl acetate random copolymers.
In the above random copolymer, the proportion of monomer component (a) the homopolymer of which is water-soluble is within the range of 10 to 90 mol % and that of monomer component (b) the homopolymer of which is water-insoluble is within the range of 90 to10 mol %.
If the proportion of monomer component (a) the homopolymer of which is water-soluble exceeds 90 mol %, the resulting random copolymer will not be much different in characteristics from the homopolymer of monomer component (a) so that the rate of adsorption on the inside wall of blood test ware and on the matrix surface is decreased and the solubility in blood is too high. As a consequence, when blood is drawn into the blood test ware, the random copolymer is washed out from the inner surface of the ware and the matrix surface so that it cannot play the role of preventing deposition of blood components.
On the other hand, if the proportion of monomer component (a) the homopolymer of which is water-soluble is less than 10 mol %, the copolymer will not be much different in characteristics from the homopolymer of monomer component (b) and become substantially insoluble in blood so that it may not play the role of preventing deposition of blood components. When a combination of this blood component deposition-preventing agent and a blood coagulation accelerator or a blood anticoagulant is applied to the inside wall of the blood test ware or the matrix surface and dried, a blood-insoluble film is formed on the surface of the blood coagulation accelerator or anticoagulant so that blood coagulation factors XII, XI, etc. cannot bind to the surface of the blood coagulation accelerator, with the result that the coagulation of blood is not hastened and the reduced solubility of the blood anticoagulant leads to an insufficient anticoagulant effect.
For the above reasons, the random copolymer for use in the present invention should be such that said monomer component (a) whose homopolymer is water-soluble and said monomer component (b) whose homopolymer is water-insoluble account for 10 to 90 mol % and 90 to 10 mol % respectively.
The blood test ware of the present invention comprises a vessel and, as disposed on its inner surface, the blood component deposition-preventing agent according to the first aspect of the present invention.
In this construction, the amount of the blood component deposition-preventing agent present on the inner surface of the vessel is preferably in the range of 1xc3x9710xe2x88x9210 to 1xc3x9710xe2x88x922 g/cm2. If the amount of the blood component deposition-preventing agent is less than 1xc3x9710xe2x88x9210 g/cm2, the deposition-preventing effect will not be sufficient, while the presence of more than 1xc3x9710xe2x88x922 g/cm2 of the deposition-preventing agent will be liable to affect various test values.
The material for the vessel of the blood test ware of the invention can be any of thermoplastic resin, thermosetting resin, modified natural resin, and glass. The thermoplastic resin mentioned above includes but is not limited to polyethylene, polypropylene, poly(4-methylpentene-1), polystyrene, poly(methyl methacrylate), poly(vinyl chloride), poly(ethylene terephthalate), poly(butylene terephthalate), poly(styrene-co-acrylonitrile), poly(styrene-co-maleic anhydride), poly(styrene-co-acrylic acid), poly(styrene-co-methyl methacrylate), poly(ethylene-co-propylene), poly(ethylene-co-acrylic acid), poly(ethylene-co-acrylic ester), poly(vinyl acetal), and poly(vinyl butyral). The thermosetting resin mentioned above includes but is not limited to unsaturated polyester resin, epoxy resin, and epoxy-acrylate resin. The modified natural resin includes but is not limited to cellulose acetate, cellulose propionate, cellulose acetate butyrate, ethylcellulose, and ethylchitin.
The blood test ware of the present invention can be manufactured by causing the blood component deposition-preventing agent of the invention to be present on the inner wall of a blood test vessel or tube by a variety of alternative methods. Thus, for example, the method which comprises kneading the blood component deposition-preventing agent of the invention into a plastic batch for the molding of a vessel and molding the kneaded mixture by the injection molding, blow molding or other technique and the method which comprises dissolving the blood component deposition-preventing agent in pure water or alcohol, applying the solution to the inside wall of the vessel by spray coating or dip coating, and drying the coat can be mentioned.
In addition to the presence of the blood component deposition-preventing agent comprising the random copolymer according to the present invention, the blood test ware of the present invention may have a serum/plasma separator comprising a thixotropic fluid or a separator material functioning as a partition between the serum or plasma layer and the blood solid component layer.
The serum/plasma separator includes a composition comprising liquid acrylic resin, chlorinated polybutene or liquid dicyclopentadiene (DCPD) as a matrix and a finely divided inorganic powder such as microfine silica, alumina or glass particles as an auxiliary component for specific gravity adjustment and thixotropy.
By allowing such a partition-forming agent to be present, the storage life of serum or plasma can be increased without confounding test values.
The blood component deposition-preventing matrix of the present invention comprises a support and, as disposed on its surface, a blood component deposition-preventing agent comprising the random copolymer according to the first aspect of the present invention. The blood component deposition-preventing matrix is put to use as accommodated in a blood test tube or vessel. The support of said blood component deposition-preventing matrix can be any of the known supports. The shape of the support is not limited and may, for example, be pellets, a sheet, a nonwoven fabric, or a woven fabric. The possible raw material of the support includes thermoplastic resin, thermosetting resin, and modified natural resin, among others. The thermoplastic resin mentioned just above includes but is not limited to polyethylene, polypropylene, poly(4-methylpentene-1), polystyrene, poly(methyl methacrylate), poly(vinyl chloride), poly(ethylene terephthalate), poly(butylene terephthalate), poly(styrene-co-acrylonitrile), poly(styrene-co-maleic anhydride), poly(styrene-co-acrylic acid), poly(styrene-co-methyl methacrylate), poly(ethylene-co-propylene), poly(ethylene-co-acrylic acid), poly(ethylene-co-acrylic ester), poly(vinyl acetal), and poly(vinyl butyral). The thermosetting resin includes unsaturated polyester resin, epoxy resin, and epoxy-acrylate resin.
The amount of said blood component deposition-preventing agent comprising the random copolymer on the surface of said blood component deposition-preventing support is preferably in the range of 1xc3x9710xe2x88x9210 to 1xc3x9710xe2x88x922 g/cm2. If the amount of the blood component deposition-preventing agent is less than 1xc3x9710xe2x88x9210 g/cm2, the deposition-preventing effect will not be sufficient, while the presence of more than 1xc3x9710xe2x88x922 g/cm2 of the deposition-preventing agent will be liable to affect various test values.
The blood component deposition-preventing matrix of the present invention can be manufactured by causing the blood component deposition-preventing agent of the invention to be present on the surface of a support by a variety of alternative methods. Thus, for example, the method which comprises kneading the blood component deposition-preventing agent of the invention into a plastic batch for the fabrication of the support and molding the kneaded mixture by the injection molding, blow molding or other technique and the method which comprises dissolving the blood component deposition-preventing agent in pure water or alcohol, applying the solution to the surface of the support by spray coating or dip coating, and drying the coat can be mentioned.
While the blood component deposition-preventing agent of the present invention can be used independently as described above, it can be used in combination with an adsorbent inorganic material, e.g. mineral substances such as glass, kaolin, bentonite, silica, cerite, etc., or in combination with an organic blood coagulation-accelerating substance such as ellagic acid. It can also be used in combination with an anticoagulant such as an ethylenediaminetetraacetic acid salt, citric acid salt, heparin salt, oxalic acid salt, or the like or an antiglycolytic agent such as fluorides, mannose, and so on.
When poly(vinylpyrrolidone-co-vinyl acetate) is selected as the blood component deposition-preventing agent of the invention and used in combination with said adsorbent inorganic material comprising at least one member of the group consisting of glass, kaolin, bentonite, silica and cerite, the vinylpyrrolidone content of said poly(vinylpyrrolidone-co-vinyl acetate) is preferably in the range of 10 to 70 mol %. If the proportion of vinylpyrrolidone is less than 10 mol %, the agent will be stuck to the inside wall of the vessel so that no clot-exfoliating effect can be obtained. If the proportion of vinylpyrrolidone exceeds 70 mol %, the agent will dissolve into the blood and not remain on the inner surface of the vessel so that no clot-exfoliating effect can be obtained.
The adsorbent inorganic material mentioned above is preferably a material not containing particles larger than 50 xcexcm and having a mean particle diameter of not more than 30 xcexcm. Particularly for shortening the clotting time, the adsorbent inorganic substance is preferably silica and a porous silica containing not less than 20 weight % of an amorphous fraction is particularly preferred. Such an adsorbent inorganic substance promotes activation of blood coagulation factors on contact with blood and, also, accelerates aggregation of platelets.
In such cases, the amount of poly(vinylpyrrolidone-co-vinyl acetate) to be present on the inside wall of the blood test vessel is preferably in the range of 1xc3x9710xe2x88x9210 to 1xc3x9710xe2x88x922 g/cm2. On the other hand, the amount of the adsorbent inorganic substance to be present on the inside wall of the blood test vessel is preferably in the range of 1xc3x9710xe2x88x926 to 1xc3x9710xe2x88x922 g/cm2. If it is less than 1xc3x9710xe2x88x926 g/cm2, no blood coagulation-accelerating effect will be obtained. If the limit of 1xc3x9710xe2x88x922 g/cm2 is exceeded, chances for inaccurate tests will be increased. The combined amount of said two materials is preferably not greater than 1xc3x9710xe2x88x922 g/cm2.
With the blood test ware carrying the poly(vinylpyrrolidone-co-vinyl acetate) and adsorbent inorganic substance in combination, the blood coagulation factors are rapidly activated so that the clotting time is considerably shortened and, at the same time, the adhesion of the resulting clot to the inside wall of the blood test vessel is successfully prevented. As consequences, release of the serum from the clot is assisted, contamination of the serum with components of the clot is eliminated, and the serum yield is remarkably increased.
In order that said adsorbent inorganic substance may effectively exhibit its blood coagulation-accelerating action, each of the linseed oil absorption value, BET specific surface area value, and resistivity value is preferably within a certain range.
The linseed oil absorption value and BET specific surface area value represent the magnitude of surface area of the adsorbent inorganic substance and the surface area value is also related with the degree of surface porosity of the adsorbent inorganic substance. Therefore, the degree of surface porosity can be known from the oil absorption and specific surface area values. The preferred adsorbent inorganic substance for use in the present invention preferably has a linseed oil absorption value of 20 to 40 ml/100 g and a BET specific surface area value of 5000 to 30000 cm2/g.
The linseed oil absorption value is the value measured in accordance with Japanese Industrial Standards (JIS) K-5101. The BET specific surface area value means the value found by determining the amount of gas which completely covers the surface as a monomolecular layer from the amount of gas adsorbed on the surface of an adsorbent inorganic substance, the prevailing equilibrium pressure, and the saturation vapor pressure of adsorbed gas and multiplying the result by the mean sectional area of adsorbed gas molecules. As the adsorption gas, nitrogen gas, oxygen gas, argon gas, methane gas, etc. can be selectively employed. By this procedure, the surface area inclusive of fine pores which cannot be measured by the linseed oil absorption method can be determined. In the coagulation of blood, factor XII, that is to say the contact factor, is activated but for this activation it is necessary that the three substances of factor XII, prekalikrein and macromolecular kininogen must form a complex and be adsorbed on the surface of a foreign matter and it is said that the adsorption in the deficiency in one or two of the three does not result in the activation. In this connection, when an adsorbent inorganic substance used for the purpose of accelerating blood coagulation is a substance having a vary large surface area, the free factor XII, prekalikrein and macromolecular kininogen not forming a complex are adsorbed in an increased proportion on its surface, that is to say the proportion of the tripartite complex necessary for the activation of factor XII is decreased so that the blood coagulation-accelerating effect is rather sacrificed. Conversely when the surface area of the adsorbent inorganic substance is too small, the probability of adsorption of coagulation factors is decreased so that the desired blood coagulation-accelerating effect cannot be expected.
Therefore, the preferred adsorbent inorganic substance has a linseed oil absorption value of 20 to 40 ml/100 g and a BET specific surface area value of 5000 to 30000 cm2/g.
The preferred resistivity value of the adsorbent inorganic substance is not larger than 1xc3x971010 xcexa9xc2x7cm and, for still better results, not larger than 5xc3x97104 xcexa9xc2x7cm. The resistivity value is the reciprocal of the electrical conductivity value and represents the value at atmospheric temperature. It is supposed that the above resistivity of the adsorbent inorganic substance contributes to a sustained alignment of electric potential distribution between the protein and the adsorbent inorganic substance and prevention of change in the conformation of the protein.
When poly(vinylpyrrolidone-co-vinyl acetate) as said blood component deposition-preventing agent and a salt of ethylenediaminetetraacetic acid, a salt of citric acid, a heparin salt, a salt of oxalic acid, or the like as said blood anticoagulant are used in combination, the vinyl acetate content of said poly(vinylpyrrolidone-co-vinyl acetate) is preferably in the range of 30 to 90 mol %.
The ethylenediaminetetraacetate mentioned above can be any of those salts which are conventionally employed, such as disodium ethylenediaminetetraacetate, dipotassium ethylenediaminetetraacetate, tripotassium ethylenediaminetetraacetate, and so on.
The salt of citric acid can also be the salt conventionally used as a blood anticoagulant and may for example be trisodium citrate.
The heparin salt mentioned above may also be a salt conventionally used as an anticoagulant such as heparin sodium, heparin lithium, etc.
The salt of oxalic acid mentioned above can also be any salt that is conventionally used as an anticoagulant, thus including sodium oxalate, potassium oxalate, etc.
Any of the same known techniques as described hereinbefore can be used for causing said blood coagulation accelerator, blood anticoagulant, and antiglycolytic agent to be present on the inside wall of a blood test vessel or on the surface of a matrix to be accommodated in the blood test vessel. An exemplary procedure comprises causing the blood component deposition-preventing agent of the invention to be present on the inside wall of a blood test vessel or the surface of a support in the first place and, then, applying the blood coagulation accelerator, blood anticoagulant and/or antiglycolytic agent to the inside wall or surface by way of spray-coating or dipping. An alternative procedure comprises dissolving or suspending all the components in a suitable medium, applying the solution or suspension to the substrate surface by way of spray-coating or dipping, and drying the coat.
Since the blood component deposition-preventing agent of the present invention is a random copolymer comprising 10 to 90 mol % of a monomer component (a) which would give a water-soluble homopolymer and 90 to 10 mol % of a monomer component (b) which would give a water-insoluble homopolymer, it is structurally distinct from the known block copolymer of a hydrophilic monomer component such as a nonionic surfactant with a hydrophobic monomer component or the known graft polymer corresponding to such a block copolymer. While the nonionic surfactant mentioned above is coming into popular use as a useful sensitizer in immunoserological tests, the blood component deposition-preventing agent of the present invention is substantially free from the action of a sensitizer and, as such, does not induce test errors such as false positive reactions.
In the second aspect of the present invention, a blood coagulation accelerator is provided by supporting an antimicrobial metal on a support or carrier and the resulting antimicrobial composition which is substantially insoluble in blood is employed.
The support mentioned above must be eliminated from the serum at centrifugation after the coagulation of blood for separation of serum. Since the specific gravity of human serum is 1.02 to 1.03, the above support should have a specific gravity of not less than 1.03 and preferably not less than 1.05.
The support material is not critical in kind only if the above requirement in regard to specific gravity is satisfied, thus including a variety of inorganic materials such as zeolite, montmorillonite, ceramics, glass, insoluble phosphates, etc. and a variety of organic materials such as graphite and ion exchange resins. Particularly preferred are silicic acid compounds or silica series substances such as zeolite, montmorillonite, ceramics, etc. and insoluble phosphates, all of which per se have blood coagulation-accelerating properties as well.
The antimicrobial metal for use in the present invention is not particularly limited, thus including the corresponding salts and organometal compounds whose metal elements are copper and silver which belong to the Ib group of the periodic table of the elements, zinc, cadmium and mercury in the IIb group, germanium, tin and lead in the IVa group, lanthanids such as cerium and so on. In view of the balance between toxicity and utility, silver, copper, zinc, and cerium are preferred.
The antimicrobial composition contained in the blood coagulation accelerator according to the second aspect of the present invention comprises said support and, as supported thereby, said bacteriostatic metal. The mode of supporting of said bacteriostatic metal on the support includes ion exchange, complex formation, and inclusion (as a clathlate). Other supporting modes are not satisfactory because of the risk of release of the metal into the blood.
The antimicrobial composition mentioned above is preferably in the form of a finely divided powder with a large surface area and the preferred particle size is 0.01 to 500 xcexcm. If the particle diameter is less than 0.01 xcexcm, a higher bacteriostatic action can be expected but in the centrifugation step following completion of blood coagulation for separation of serum, the composition may remain in serum under the routine centrifugal conditions of about 1000 to 1800 Gxc3x975 minutes to cause clouding of the serum and other troubles such that the supported metal and the metal inherently contained in the serum are assayed together to introduce a positive error to the test value.
On the other hand, if the particle diameter exceeds 500 xcexcm, the antimicrobial composition tends to be dispersed unevenly in the preparation of a suspension of the blood coagulation accelerator, with the result that the expression of antimicrobial activity is localized near the surface of the antimicrobial composition so that no bacteriostatic/fungistatic effect can be expected. Particularly preferred is an antimicrobial composition having a mean particle diameter of 0.01 to 50 xcexcm.
The minimum dose of said antimicrobial composition, like that of antisepatic and antifungal agents in general, can be chosen according to MBC (minimal bactericidal concentration) and MFC (minimal fungicidal concentration). However, it is preferable to insure that the concentration of the antimicrobial agent in a suspension of the blood coagulation accelerator of the invention in purified water, for instance, will be not less than 0.1 xcexcg/ml.
As to the maximum dose of said antimicrobial composition, objectionable events such as hemolysis would be encountered if a large amount of insoluble matter finds its way into the blood. Therefore, it is preferable to determine the formulation so that the concentration in blood in the event of release into the blood will not exceed 0.5 g/ml.
The above-mentioned blood coagulation accelerator can be prepared by mixing the above antimicrobial composition with a mineral blood coagulation-accelerating agent such as glass, kaolin, bentonite, silica, cerite, etc. or an organic blood coagulation-accelerating substance such as ellagic acid.
The above blood coagulation accelerator can be suspended in pure water or physiological saline to prepare a suspension and this suspension be contacted with the sample blood to shorten the clotting time.
Furthermore, the above blood coagulation accelerator can be used to construct a blood test ware having high blood coagulation-accelerating activity by suspending the accelerator in pure water or alcohol/purified water and spraying the inside wall of the blood test vessel with the suspension or immersing a support such as a nonwoven fabric or a plastic sheet in said suspension and, after drying and cutting the support to size, accommodating the cutting in the blood test vessel.
The above-mentioned blood coagulation-accelerating suspension may contain a water-soluble macromolecular compound such as polyvinylpyrrolidone or modified cellulose as a binder for the coagulation accelerator or a viscosity control agent for the suspension.
The antimicrobial composition comprising silver, copper, zinc or the like as immobilized on zeolite, montmorillonite, ceramic, insoluble phosphate or the like, which is contained in the blood coagulation accelerator of the present invention destroys microorganisms invading the purified water or alcohol/purified water in which the accelerator has been suspended and is capable of preventing microbial contamination during storage of the blood test ware manufactured using the accelerator and, yet, will no dissolve into the blood so that the function of the blood coagulation accelerator is not adversely affected, nor does it interfere with blood examination values. Moreover, because the antimicrobial composition itself has blood coagulation-accelerating activity, the specific activity of the whole blood coagulation accelerator as a complex artefact is not compromised. The reason why sufficient antimicrobial efficacy can be expected despite the fact that the antimicrobial metal contained in the antimicrobial composition of the invention is little released in the form of free ions is probably that active oxygen is generated in the vicinity of the supported metal.
The essential feature of the third aspect of the present invention resides in the following constructions of (3-1), (3-2), (3-3), (3-4), and (3-5).
(3-1)
A blood test ware characterized in that 1xc3x9710xe2x88x9210 to 1xc3x9710xe2x88x922 g/cm2 of a polyvinylpyrrolidone having a weight average molecular weight of 100000 to 2000000 is disposed on the inside wall of a plastic vessel and, in addition, at least one blood anticoagulant selected from the group consisting of the salts of ethylenediaminetetraacetic acid, heparin, citric acid, and oxalic acid is disposed in said plastic vessel.
(3-2)
A blood test ware characterized in that a composition comprising the following components (1), (2), and (3) is disposed on the inside wall thereof, and a blood test matrix characterized in that a composition comprising the following components (1), (2), and (3) is disposed on the surface thereof, and which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.03 and a maximum projected length of not less than 1 mm.
(1) a polyvinylpyrrolidone having a weight average molecular weight of 100000 to 2000000
(2) a blood anticoagulant
(3) a finely divided powder which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.08 and a particle diameter of 1 mxcexc to 100xcexc
(3-3)
A blood test ware characterized in that a composition comprising the following components (1), (2), and (3) is disposed on the inside wall thereof, and a blood test matrix characterized in that a composition comprising the following components (1), (2), and (3) is disposed on the surface thereof, and which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.03 and a maximum projected length of not less than 1 mm.
(1) a random copolymer comprising 10 to 90 mol % of a monomer component (a) the homopolymer of which is water-soluble and 90 to 10 mol % of a monomer component (b) the homopolymer of which is water-insoluble
(2) a blood anticoagulant
(3) a finely divided powder which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.08 and a particle diameter of 1 mxcexc to 100xcexc
(3-4)
A blood test ware characterized in that a composition comprising the following components (1), (2), and (3) is disposed on the inside wall thereof, and a blood test matrix characterized in that a composition comprising the following components (1), (2), and (3) is disposed on the surface thereof, and which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.03 and a maximum projected length of not less than 1 mm.
(1) a nonionic surfactant
(2) a blood anticoagulant
(3) a finely divided powder which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.08 and a particle diameter of 1 mxcexc to 100xcexc
(3-5)
A blood test ware characterized in that a composition comprising the following components (1), (2), (3), and (4) is disposed on the inside wall thereof, and a blood test matrix characterized in that a composition comprising the following components (1),(2), (3), and (4) is disposed on the surface thereof, and which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.03 and a maximum projected length of not less than 1 mm.
(1) at least one blood component deposition-preventing agent selected from the group consisting of silicone oil, polar group-containing modified silicone oil, polyhydric alcohol partial esters, polyhydric alcohol complete esters, and poly(propylene oxide)
(2) a water-soluble macromolecular compound
(3) a blood anticoagulant
(4) a finely divided powder which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.08 and a particle diameter of 1 mxcexc to 100xcexc
The third aspect of the present invention is now described in detail.
The blood test ware (3-1) comprises a plastic vessel and, as disposed on the inside wall thereof, 1xc3x9710xe2x88x9210 to 1xc3x9710xe2x88x922 g/cm2 of a polyvinylpyrrolidone having a weight average molecular weight of 100000 to 2000000. If the amount of said polyvinylpyrrolidone is less than 1xc3x9710xe2x88x922 g/cm2, it will be impossible to obtain the desired blood component deposition-preventing effect, while more than 1xc3x9710xe2x88x922 g/cm2 of polyvinylpyrrolidone will interfere with blood examinations.
The weight average molecular weight of polyvinylpyrrolidone can be determined by the conventional methods such as ultracentrifugation or the light scattering method. As an alternative, the viscosity average molecular weight (Mv) is first calculated from the viscosity value known as K value by means of the following equation (1) and the weight average molecular weight (Mw) is then calculated by means of the following equation (2) [V. Buehler, U. Klodwig. Acta Pharm., Techn., 30. No. 4 (1984)].
Mv=22.22xc3x97(K+0.075xc3x97K2)1.65 xe2x80x83xe2x80x83(1)
Mwxe2x89xa0Mvxe2x80x83xe2x80x83(2)
The weight average molecular weight of said polyvinylpyrrolidone is 100000 to 2000000. If it is less than 100000, the polyvinylpyrrolidone will dissolve into blood and disappears from the inside wall of the blood test ware so that the blood component deposition-preventing effect cannot be obtained. If the molecular weight exceeds 2000000, spray or other coating workability is sacrificed. Therefore, the above range is essential. The preferred range is 300000 to 1500000 and the still more preferred range is 600000 to 1500000.
Further disposed in this blood test ware is at least one blood anticoagulant selected from the group consisting of the salts of ethylenediaminetetraacetic acid, heparin, citric acid, and oxalic acid, and fluorides.
The above-mentioned salt of ethylenediaminetetraacetic acid can be any of the salts which are conventionally used as blood anticoagulants, such as disodium ethylenediaminetetraacetate, dipotassium ethylenediaminetetraacetate, and tripotassium ethylenediaminetetraacetate, among others.
The above-mentioned salt of citric acid can also be any of the salts conventionally used as blood anticoagulants, such as trisodium citrate, among others.
The heparin salt mentioned above can be a salt of heparin which is commonly used as a blood anticoagulant, thus including heparin sodium, heparin lithium and so on.
The above-mentioned salt of oxalic acid can be any of those oxalates which are conventionally used as blood anticoagulants, thus including sodium oxalate and potassium oxalate, among others.
Among the fluorides mentioned above are sodium fluoride and potassium fluoride which are conventionally used as antiglycolytic agents.
In the above blood test ware may be further accommodated a material capable of establishing a partition between a plasma layer and a solid component layer, such as a plasma separator comprising a thixotropic fluid or a separating member. The plasma separator may for example be a composition comprising chlorinated polybutene or dicyclopentadiene (DCPD) resin as a main component and a finely divided inorganic powder such as powdered silica, alumina or glass as a viscosity control and thixotropic agent. When such a partitioning material is provided, the blood test ware can store the plasma for a long time without adverse effects on test data.
The method of using the blood test ware comprises drawing the blood sample into the ware and after thorough mixing of the anticoagulant and the blood, centrifuging the ware to separate the plasma.
Since a specified quantity of a specified grade of polyvinylpyrrolidone is present on the inside wall of the vessel in the above blood test ware, corpuscular elements and proteins in the blood are prevented from adhering to the inside wall surface. Moreover, since the blood anticoagulant is accommodated in the vessel, coagulation of the blood is prevented. Furthermore, in the embodiment where a partition-forming substance is provided within the vessel, the plasma can be stored in stable condition for a long time without influences on test values.
The blood test ware (3-2) comprises a vessel and, as disposed on the inside wall of said vessel, a composition comprising the following components (1), (2) and (3), and the corresponding blood test matrix comprises a support and, as disposed on its surface, a composition comprising the following components (1), (2) and (3), and is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.03 and a maximum projected length of not less than 1 mm.
(1) a polyvinylpyrrolidone having a weight average molecular weight of 100000 to 2000000
(2) a blood anticoagulant
(3) a finely divided powder which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.08 and a particle size within the range of 1 mxcexc to 100xcexc
The description for (3-1) applies to said polyvinylpyrrolidone having a weight average molecular weight of 100000 to 2000000 (1).
The description for (3-1) applies to said blood anticoagulant (2).
The finely divided powder (3) is now described. Using a medium which is a good solvent for both the polyvinylpyrrolidone and blood anticoagulant, a homogeneous solution can be prepared. However, when the inside wall of a plastic vessel is coated with such a solution by spray-coating or dip-coating and the coated vessel is allowed to stand in the upright position, the solution is not retained on the inside wall but flows down to the bottom of the vessel. In that event, the solution forms a thick dry film on the bottom to seriously interfere with redissolution of the anticoagulant in the blood so that the blood undergoes local coagulation and in the subsequent step of accommodating a plasma separator most of the anticoagulant is buried under the plasma separator and fails to contact the blood introduced so that the expected effect is not accomplished. The finely divided powder (3) has the property to considerably improve the retention of the dispersion on the plastic vessel by suppressing the sagging tendency so that the above problem is neatly solved.
The above effect of the finely divided powder (3) is probably attributed to the following. Thus, as the finely divided powder is adsorbed on the inside wall surface, a large number of fine projections and recesses are formed on the inside wall to increase the surface area and the retentivity of the solution is increased as the result of surface tension.
If the specific gravity of said finely divided powder (3) is less than 1.08, the powder (3) could remain in the plasma even after centrifugal separation of the blood to interfere with blood tests. Therefore, the specific gravity is restricted to 1.08 or more.
If the particle diameter of finely divided powder (3) is less than 1 mxcexc the fine particles tend to form a dense film upon concentration to dryness to interfere with redissolution of the blood anticoagulant. On the other hand, if 100xcexc is exceeded, the separation and sedimentation rate of particles in a mixed dispersion of polyvinylpyrrolidone and blood anticoagulant is increased to sacrifice the retentivity on the inside wall surface of the vessel. Therefore, the particle diameter should be limited to the above range. The preferred range is 1 to 50xcexc.
The level of addition of finely divided powder (3) is not particularly critical but a sufficient effect can be obtained when it is present in a proportion of 5 weight % or less.
The material of said finely divided powder (3) is not so critical and can be any of such materials as, for example, poly(meth)acrylic acid esters, poly(vinyl chloride), fluororesins, polyamides, polyesters, polyoxyalkylenes, polyurethane, urea resin, melamine resin, epoxy resin, phenolic resin, cellulose, chitin, modified cellulose, modified chitin, and their copolymers and crosslinked polymers. Even polystyrene, polyethylene and polypropylene which cannot be used alone on account of their low specific gravities can be utilized when a conventional inorganic filler such as silica, talc or the like has been kneaded into them for specific gravity adjustment. These powders can be manufactured in the conventional manner, for example by suspension polymerization or pulverization and size selection. In the above blood test ware may be disposed a material capable of providing a partitioning wall between the plasma layer and the solid component layer, such as a plasma separator comprising a thixotropic fluid or a separatory member.
The blood test matrix according to (3-2) carries a composition comprising the above-mentioned components (1), (2) and (3) on its surface and provides for the same effect as the blood test ware described above. The blood test matrix should not affect the blood examination and, therefore, is designed to be substantially insoluble in blood and physicochemically substantially inert to blood. This blood test matrix has a specific gravity of not less than 1.03 and a maximum projected length of not less than 1 mm. If the specific gravity is less than 1.03, the matrix floats without sinking in the blood sample to interfere with the examination. If the maximum projected length is less than 1 mm, workability is sacrificed.
The above blood test matrix is used as accommodated in the blood test vessel. The known support materials can be used for the fibrication of said blood test matrix. There is no particular limitation on matrix configuration, and pellets, sheet, nonwoven cloth, woven cloth, etc. can be mentioned as examples. The raw material is not particularly restricted, either, and a variety of materials similar to those mentioned for said component (3) can be utilized.
The blood test ware according to (3-3) comprises a vessel and, as disposed on its inside wall surface, a composition comprising the following components (1), (2) and (3). The corresponding blood test matrix comprises a support and, as disposed on its surface, a composition comprising the following components (1), (2) and (3), and is substantially insoluble in blood and physicochemically inert to blood and has a specific gravity of not less than 1.03 and a maximum projected length of not less than 1 mm.
(1) a random copolymer comprising 10 to 90 mol % of a monomer components (a) which would give a water-soluble homopolymer and 90 to 10 mol % of a monomer component (b) which would give a water-insoluble homopolymer.
(2) a blood anticoagulant
(3) a finely divided powder which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.08 and a particle diameter in the range of 1 mxcexc to 100xcexc
The above-mentioned random copolymer (1) comprises a monomer component (a) which would give a water-soluble homopolymer and a monomer component (b) which would give a water-insoluble homopolymer. The monomer component (a) which would give a water-soluble homopolymer that can be used includes but is not limited to vinylpyrrolidone, vinyl alcohol, ethylene oxide, salts of acrylic acid, salts of styrenesulfonic acid, salts of vinylphosphonic acid, allylamine salts, hydroxymethyl (meth)acrylate, glycosylethyl (meth)acrylate, saccharides such as glucose, and amino acids such as glutamic acid. These monomers can be used alone or as a mixture.
The monomer component (b) which would give a water-insoluble homopolymer that can be used includes but is not limited to ethylene, propylene, propyleneoxide, vinyl acetate, vinyl chloride, alkyl (meth)acrylates, styrene, acrylonitrile, and acrolein. These monomers can be used alone or as a mixture.
The random copolymer comprising said monomer components (a) and (b) can be produced typically by the known addition polymerization reaction or polycondensation reaction. In view of the availability of materials, it is advantageous to synthesize the random copolymer by using vinylpyrrolidone or vinyl alcohol as the monomer component: (a) and vinyl acetate as themonomer component (b). As commercial products, Luviskol VA grade numbers VA73, VA64, VA55, VA37, and VA28 are available from BASF as typical vinylpyrrolidone-vinyl acetate random copolymers and Unitika Poval grade numbers E-180, UMR-10M, UMR-30L, and UMR-150L are available from Unitika Ltd. as typical vinyl alcohol-vinyl acetate random copolymers.
In the above random copolymer, the proportion of monomer component (a) the homopolymer of which is water-soluble is within the range of 10 to 90 mol % and that of monomer component (b)) the homopolymer of which is water-insoluble is within the range of 90 to 10 mol %.
If the proportion of monomer component (a) the homopolymer of which is water-soluble exceeds 90 mol %, the resulting random copolymer will not be much different in characteristics from the homopolymer of monomer component (a) so that the rate of adsorption on the inside wall of the blood test ware and on the matrix surface is decreased and the solubility in blood is too high. As a consequence, when blood is drawn into the blood test ware, the random copolymer is washed out from the inside wall of the ware or the matrix surface so that it cannot play the role of preventing deposition of blood components.
On the other hand, if the proportion of monomer component (a) whose homopolymer is water-soluble is less than 10 mol %, the copolymer will not be much different in characteristics from the homopolymer of monomer component (b) and be substantially insoluble in blood so that it may not play the role of preventing deposition of blood components. When a combination of this blood component deposition-preventing agent with a blood coagulation accelerator or a blood anticoagulant is applied to the inside wall of a blood test vessel or the matrix surface and dried, a blood-insoluble film is formed on the surface of the blood coagulation accelerator or blood anticoagulant so that blood coagulation factors XII, XI, etc. cannot bind to the surface of the blood coagulation accelerator, with the result that the coagulation of blood is not hastened and the reduced solubility of the blood anticoagulant leads to an insufficient anticoagulant effect.
For the above reasons, the random copolymer for use in the present invention should be such that said monomer component (a) whose homopolymer is water-soluble and said monomer component (b) whose homopolymer is water-insoluble account for 10 to 90 mol % and 90 to 10 mol %, respectively.
The amount of said random copolymer is preferably 1xc3x9710xe2x88x9210 to 1xc3x9710xe2x88x922 g/cm2. If it is less than 1xc3x9710xe2x88x9210 g/cm2, deposition of corpuscular components and proteins will not be sufficiently precluded. If the amount of the random copolymer exceeds 1xc3x9710xe2x88x922 g/cm2, various test parameter values will be confounded.
The above blood test ware according to (3-4) comprises a vessel and, as disposed on its inside wall, a composition comprising the following components (1), (2) and (3) and the corresponding blood test matrix comprises a support and, as disposed on its surface, a composition of the following components (1), (2) and (3) and is substantially insoluble in blood and physiochemically substantially inert to blood and has a specific gravity of not less than 1.03 and a maximum projected length of not less than 1 mm.
(1) a nonionic surfactant
(2) a blood anticoagulant
(3) a finely divided powder which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.08 and a particle diameter in the range of 1 mxcexc to 100xcexc
The above nonionic surfactant (1) that can be used includes but is not limited to ethylene glycol/propylene glycol series, alkyl/alkylene oxide series, and alkylene oxide/silicone series block copolymers and graft copolymers, inclusive of the corresponding modified polymers. Particularly preferred are surfactants with HLB (hydrophilic-lypophilic balance) numbers not less than 10.
The preferred proportion of said nonionic surfactant (1) is 1xc3x9710xe2x88x9210 to 1xc3x9710xe2x88x922 g/cm2. If it is less than 1xc3x9710xe2x88x9210 g/cm2 deposition of corpuscular components and proteins will not be sufficiently precluded. If the amount of the surfactant exceeds 1xc3x9710xe2x88x922 g/cm2, various test parameter values could be confounded.
The blood test ware according to (3-5) comprises a vessel and, as disposed on the inside wall surface thereof, a composition comprising the following components (1), (2), (3) and (4), and the corresponding blood test matrix comprises a support and, as disposed on its surface, a composition comprising the following components (1), (2), (3) and (4) and is substantially insoluble in blood and physiochemically substantially inert to blood and has a specific gravity of not less than 1.03 and a maximum projected length of not less than 1 mm.
(1) At least one blood component deposition-preventing agent selected from the group consisting of silicone oil, modified silicone oil containing polar groups, partial esters of polyhydric alcohols, complete esters of polyhydric alcohols, and poly(propylene oxide)
(2) a water-soluble macromolecular substance
(3) a blood anticoagulant
(4) a finely divided powder which is substantially insoluble in blood and physicochemically substantially inert to blood and has a specific gravity of not less than 1.08 and a particle diameter in the range of 1 mxcexc to 100xcexc
The silicone oil (1) that can be used includes but is not limited to dimethylpolysiloxane, methylhydrogenpolysiloxane, and methylphenylpolysiloxane. The polar group-modified silicone oil (1) includes oils obtainable by introducing polar groups such as hydroxyl, amino, carboxyl, epoxy, etc. into dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane and other silicone oils.
The above-mentioned partial or complete esters of polyhydric alcohols (1) are compounds available on introduction of fatty acid molecules to some or all of the alcoholic hydroxyl functions of the respective polyols such as glycerol, sorbitol, polyphenol, etc.
The blood component deposition-preventing agent (1) includes, in addition to the substances mentioned above, poly(propylene oxide) and other substances.
The preferred amount of said blood component deposition-preventing agent (1) is 1xc3x9710xe2x88x9210 to 1xc3x9710xe2x88x922 g/cm2. If the amount of (1) is less than 1xc3x9710xe2x88x9210 g/cm2, no sufficient deposition-preventing effect on corpuscular elements and proteins will be obtained. If it exceeds 1xc3x9710xe2x88x922 g/cm2, various test parameter values will be interfered with.
The water-soluble macromolecular compound (2) that can be used includes but is not limited to poly(ethylene oxide), poly(vinyl alcohol), polyvinylpyrrolidone, poly(sodium acrylate), polyethyleneimine, sodium alginate, starch, pullulan, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethlylcellulose, cellulose acetate phthalate, gum arabic, gum tragacanth, locust bean gum, guar gum, pectin, carrageenan, phaseleran, tamarind seed polysaccharide, glue, gelatin and casein. Particularly preferred are polyvinylpyrrolidone, poly(ethylene oxide) and poly(vinyl alcohol).
The water-soluble macromolecular compound (2) serves to prevent the water-insoluble matter from covering the blood anticoagulant to inhibit its solubility in blood.
The preferred amount of said water-soluble macromolecular compound (2) is 1xc3x9710xe2x88x9210 to 1xc3x9710xe2x88x922 g/cm2. If it is less than 1xc3x9710xe2x88x9210 g/cm2, no sufficient deposition-preventing effect on corpuscular elements and proteins will be obtained.
If the amount of the compound exceeds 1xc3x9710xe2x88x922 g/cm2, various test parameter values could be confounded.